Mixing in disposable, flexible bags in for example filtration systems is often required but not always achieved in a sufficient way.
Larger mixing systems employ typically magnetic impellers with corresponding magnetic drive units that are comprised in a dedicated mixer apparatus. At these systems, the flexible bag is confined and supported by rigid walls and a frame and the magnetic drive unit is integrated in said frame. One such example is the Xcellerex™ XDUO Quad Mixing system.
Smaller flexible bags of typically up to 20 L volume may be used without the support of support walls in a hanging configuration. These hanging bags have typically no active mixing element.
One mixing method for disposable, flexible hanging bags has been described in WO 2014085034. Here a container having a magnetic impeller assembly with a hood is described. The hood protects the flexible bag from the impeller, especially during transportation.
A drawback with these methods including impellers in the bags is that the bags can get damaged by the impeller. Another drawback with this design is that it requires dedicated bags equipped with the impeller element. Also, it requires a specific external arrangement with a magnetic drive unit to engage the impeller at side of the bag. Another drawback with this design is that it reduces accuracy when the volume and/or weight of the fluid in the bag is to be determined by measuring the weight of the bag.